Cummins fault code 5247

What it means

Cummins' description: Aftertreatment 1 SCR Intake Temperature - Data Valid But Above Normal Operating Range - Moderately Severe Level.

SPN 4360 is Aftertreatment 1 SCR Intake Temperature. FMI 16 means the value is clearly above normal operating range. It's the middle 'high' level.

The SCR (selective catalytic reduction) catalyst uses DEF to turn NOx into nitrogen and water. The ECM compares NOx before and after the catalyst to judge how well it's working. If it isn't, EPA rules require the engine to warn the driver and then derate.

What the lamp means

An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.

Common causes

The sensor reading itself is out of range or the condition is real, so look at the system:

• Bad or diluted DEF, or not enough DEF being dosed
• Crystallized or clogged DEF doser
• Failing NOx sensor (very common)
• SCR catalyst contaminated by oil or fuel, or worn out
• Exhaust leak ahead of the sensors
• Upstream engine problem raising NOx: EGR fault, boost leak

What you can check before calling

• Check DEF level and quality first. It's the cheapest fix
• Look for exhaust leaks or soot tracks at clamps ahead of the catalyst
• Write down any countdown or derate message on the dash before it changes

Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers. For the bigger picture, read our guide: DEF warning lights and derate: what diesel drivers need to know.

Engines and sources

Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Cummins Tier 4 Fault Codes. Always confirm with Cummins service information (QuickServe) for your engine serial number.